Python 3.7.5 : Post class and migration process.

Today I will solve some issues with the Django framework like:

• create a new class for posts;
• explain how the migration process works.
• use the database with Django shell;

Let's activate the environment:

[mythcat@desk django]$ source env/bin/activate

I used my old project django-chart, see my old tutorials.
Let's add some source code to the models.py to create a class for the post into my website:

...
# Post data 
from django.utils import timezone
from django.contrib.auth.models import User
...
#create a post
class Post(models.Model):
  title = models.CharField(max_length = 100)
  content = models.TextField()
  date_posted = models.DateTimeField(default = timezone.now)
  #if the user is deleted their posts is deleted 
  author = models.ForeignKey(User, on_delete = models.CASCADE)

Let's use the migration process to update the database:

(env) [mythcat@desk django]$ cd mysite/
(env) [mythcat@desk mysite]$ python3 manage.py makemigrations
Migrations for 'test001':
  test001/migrations/0003_post.py
  - Create model Post

Before to run the migrate command I will show what happened with this migration output from SQL view.
This is great to solve issues and see the exact SQL code generated.
I have in the output of command makemigrations the application name test001 and the migration number 0003.
I will use all of this information output to show how you can see the SQL code:

(env) [mythcat@desk mysite]$ python3 manage.py sqlmigrate test001 0003
BEGIN;
--
-- Create model Post
--
CREATE TABLE "test001_post" ("id" integer NOT NULL PRIMARY KEY AUTOINCREMENT, 
"title" varchar(100) NOT NULL, "content" text NOT NULL, "date_posted" datetime NOT NULL, 
"author_id" integer NOT NULL REFERENCES "auth_user" ("id") DEFERRABLE INITIALLY DEFERRED);
CREATE INDEX "test001_post_author_id_fed29ee6" ON "test001_post" ("author_id");
COMMIT;

This print SQL code that it's going to run when I will use the next command:

(env) [mythcat@desk mysite]$ python3 manage.py migrate
Operations to perform:
  Apply all migrations: admin, auth, contenttypes, sessions, test001
Running migrations:
  Applying test001.0003_post... OK

The migration process solves issues linked to changes in the database.
Let's use the Django shell to see the User changes into the database:

(env) [mythcat@desk mysite]$ python3 manage.py shell
Python 3.7.5 (default, Dec 15 2019, 17:54:26) 
[GCC 9.2.1 20190827 (Red Hat 9.2.1-1)] on linux
Type "help", "copyright", "credits" or "license" for more information.
(InteractiveConsole)
>>> from test001.models import Post
>>> from django.contrib.auth.models import User
>>> User.objects.all()
...
>>> User.objects.first()
...
>>> User.objects.filter(username='catalin')
...
>>> User.objects.filter(username='catalin').first()
...
>>> user = User.objects.filter(username='catalin').first()
>>> user
...
>>> user.id
1
>>> user.pk
1
>>> Post.objects.all()
...

Let's add a post to the database and show it:

>>> post_1=Post(title='First title', content='The first content!',author=user)
>>> post_1.save()
>>> Post.objects.all()
...

I can see the posts and information about the user with the Django shell.

>>> post = Post.objects.first()
>>> post.content
'The first content!'
>>> post.date_posted
...
>>> post.author
...
>>> post.author.email
...
>>> user.post_set.all()
...

You need to add to views.py the new model changes:

...
from .models import Post
...
def posts(request):
  context = {
  'posts':Post.objects.all()
  }
  return render(request, 'test001/posts.html', context)
...

Into the templates folder, I created the file named posts.html to load the data to HTML5.

{% extends 'base.html' %}
{% block content %}
  {% for post in posts %}
  <article>
  <div>{{ post.title }}</div>
  <div>{{ post.content }}</div>
  <div>{{ post.author }}</div>
  <div>{{ post.date_posted|date:"F d, Y" }}</div>
  </article>
  {% endfor %}
{% endblock content %}

To see these changes into the website I add the route to this HTML5 file posts.html into urls.py file:

app_name = 'test001'
urlpatterns = [
...
    path('posts/',posts, name = 'posts'),
...
]

Now I can run the server and see the output from the database into posts URL.

(env) [mythcat@desk mysite]$ python3 manage.py runserver
Watching for file changes with StatReloader
Performing system checks...

System check identified no issues (0 silenced).
January 06, 2020 - 17:52:29
Django version 3.0.1, using settings 'mysite.settings'
Starting development server at http://127.0.0.1:8000/
Quit the server with CONTROL-C.
...

This is the output of my running server...

Python 3.7.5 : Set json with settings in Django project.

[mythcat@desk django]$ source env/bin/activate
(env) [mythcat@desk django]$ cd mysite/
(env) [mythcat@desk mysite]$ ls
db.sqlite3  manage.py  mysite  test001
(env) [mythcat@desk mysite]$ pwd
/home/mythcat/projects/django/mysite

Create a file named config.json in the folder django:

(env) [mythcat@desk mysite]$ vim /home/mythcat/projects/django/config.json

Open your settings.py file from your Django project and copy your secret key from this file to config.json, see:

{ 
  "SECRET_KEY":"your_secret_key_from_settings.py"
}

Change your settings.py file with these changes:

...
import json 
...
with open('/home/mythcat/projects/django/config.json') as config_file:
    config = json.load(config_file)
...
# SECURITY WARNING: keep the secret key used in production secret!
SECRET_KEY = config['SECRET_KEY']

This allows us to get the SECRET_KEY from the config.json file.
We can add many variables into file config.json, like EMAIL_USER and EMAIL_PASS.
You need to have a validate JSON file and the settings.py will change from this:

EMAIL_HOST_USER = os.environ.get('EMAIL_USER')
...

to this source code for EMAIL_USER variable:

EMAIL_HOST_USER = config.get('EMAIL_USER')
...